This article is part of the CNC Surface Finishing Guide: Anodizing, Plating, Coatings & Ra on CNX Precision.
Serial number engraving gives each machined part a unique identity that lasts for the life of the product. OEMs, medical device makers, and automotive suppliers rely on these marks for traceability, recalls, and warranty claims. This guide explains the engraving methods, the standards behind them, and how to place serial numbers for reliable scanning.
A serial number is more than a string of digits. It connects a physical component to its digital records. In one lookup, you can see the material heat, the machining date, the operator, and the inspection results. That connection becomes critical when a field issue appears. Consequently, serial number engraving moves from a nice-to-have to a must-have process.
Why Serial Number Engraving Matters
Traceability is the main driver. Regulated industries expect every critical part to carry a permanent unique identifier. The automotive sector uses serial numbers for warranty claims and campaign recalls. Medical device rules ask for UDI codes on the device itself. Aerospace buyers demand full history from billet to flight.
Serial number engraving also protects your brand. A genuine part carries a mark that is hard to fake. Meanwhile, a counterfeit part usually has a shallow, blurry, or missing code. That visible difference helps inspectors and customers tell them apart.
- Recalls: find every affected unit from one serial range.
- Warranty: verify age, batch, and service history.
- Anti-counterfeiting: make genuine parts easy to identify.
- Inventory control: track WIP, stock, and finished goods.
Serial numbers also support end-of-life programs. Some regulations require producers to report which units reached the recycler. A readable serial makes that reporting straightforward.
Good traceability starts with a clear numbering system. The serial should encode meaningful data, such as year, line, and sequence. However, it should stay short enough to scan quickly. We help customers design serial formats that fit their ERP fields.
Serial Number Engraving Methods and Formats
Several methods can engrave a serial number. The best choice depends on material, depth, speed, and contrast. The table below compares the common options.
| Method | Typical Depth | Readability | Best Application |
|---|---|---|---|
| Laser engraving | 0.01–0.05 mm | Excellent contrast | Stainless steel, anodized parts |
| Dot peen | 0.1–0.4 mm | Good after coating | Castings, forged parts |
| Rotary engraving | 0.05–0.2 mm | Deep and crisp | Soft metals, small runs |
| Electrochemical | 0.005–0.03 mm | Clean, stress-free | Hardened, thin-walled parts |
Laser engraving remains the fastest option for CNC-machined parts. Fiber lasers produce fine characters with high contrast on bare metal. They also handle 2D Data Matrix codes, QR codes, and logos in the same operation.
Dot peen is the workhorse for rough surfaces. The pin indents the material, so the mark survives sandblasting and plating. The trade-off is character size. Dot peen needs larger characters than laser to stay readable.
Rotary engraving uses a spinning cutter to remove a channel of material. It suits soft metals, nameplates, and short runs. Electrochemical marking removes a controlled layer without stress, which suits hardened gears and thin walls.
For formats, most suppliers recommend alphanumeric text plus a 2D Data Matrix code. The code stores more data in a smaller area. If your customer reads marks with a handheld scanner, add a human-readable line under the code.
Cost per part varies by method. Laser marking adds little cycle time, so it suits high volumes. Dot peen takes a few seconds per part. Chemical and electrochemical methods need masks, which favors longer runs. Your chosen method should match both the volume and the reading environment.
Depth alone does not guarantee readability. A deep dot peen code on a rough surface can read worse than a shallow laser code on a clean face. Judge each method by scanning tests, not by how deep it feels.
Readability Standards and Placement Rules
Readable serial number engraving follows simple rules. First, put the mark on a flat, clean surface. Next, keep a border around the code that is free of other marks. Then set character height according to the reading distance.
- Minimum character height: 1.2 mm for laser, 1.6 mm for dot peen.
- Data Matrix cells: at least 0.25 mm per cell, larger for coated parts.
- Contrast: dark code on light background, or white laser mark on dark anodize.
- Position: away from threads, sealing faces, and bending zones.
- Depth: match to wall thickness to avoid distortion.
Standards also matter. ISO 15415 defines Data Matrix print quality. GS1 and UDI formats define the data structure. If you are unsure, send us your scanner requirement and we will design the mark to pass verification.
Placement affects scanning speed. Codes near the edge of a housing scan poorly when the fixture blocks them. Therefore, we place codes on open faces that stay visible after assembly.
Test marks matter. Before production, we engrave samples on the exact material and finish, then scan them with your device. This small step prevents expensive surprises later.
Lighting and angle change scanning results. A code that passes under a bench scanner may fail in a handheld unit. Therefore, we test with the same reader model your team will use on the line.
Serial Number Engraving in Your Production Flow
Engraving can happen before, during, or after machining. Each point has trade-offs.
- Before finishing: engrave deep marks first, then anodize or plate over them.
- After finishing: laser-mark bare metal or post-anodized surfaces for high contrast.
- During inspection: mark after final measurement, so the serial ties to the actual data.
Most shops mark at the end of the line. This way, the serial number links to final inspection results, packaging photos, and shipping records. CNX Precision follows this flow on housings, shafts, gears, and custom components. We verify every mark with a scanner before the parts leave the building.
Data management is part of the service. We can print the serial list, upload it to your portal, or deliver it as a CSV file. That record closes the loop between the physical part and your database.
Some industries ask for a second mark. For example, a housing may carry a Data Matrix on the inside and a human-readable serial on the outside. We coordinate both marks so they reference the same part record.
Serial Number Engraving FAQ
Can serial number engraving be removed or altered?
Any mark can be ground off with effort. However, deep marks leave visible damage that raises suspicion. That is why forged or damaged marks are easy to detect in audits.
How small can a serial number be?
Laser marks can go below 1 mm in height on clean metal. Dot peen typically needs 1.5 mm or more. The scanner and the camera read the code, so test with the actual device before production.
Do you engrave serial numbers on every part?
Yes. We engrave each component, not only samples. We can also record every serial with its inspection data and export the list to your ERP system.
Order Parts with Reliable Serial Numbers
Serial number engraving protects your traceability and your brand. Choose the method by material, depth, and contrast needs. Then verify the mark with the scanner you will use in the field. For a recommendation on your parts, contact CNX Precision. We will engrave samples and provide a quote quickly.
For related information, see our guide to cnc machining service and 5-axis cnc machining and cnc milling vs turning and cnc machining tolerances.